Polyesters are used routinely by those skilled in the art in various drug delivery systems.
For example, U.S. Pat. No. 5,942,252 describes a microcapsule comprising as its biocompatible excipient a poly(lactide-co-glycolide), poly(lactide), poly(glycolide), copolyoxalate, polycaprolactone, poly(lactide-co-caprolactone), poly(esteramide), polyorthoester, poly(p-hydroxybutyric) acid and/or polyanhydride for use in delivering antigens or vaccines into and through mucosally-associated lymphoid tissue.
WO 99/29885 describes a process for degrading poly(ester-amides) and poly(ester-urethanes) encapsulating chemicals, drugs, enzymes, microorganisms and seeds by introducing the polymer to an aqueous nutrient solution and inoculating the solution with a culture containing a selected bacteria.
WO 98/36013 describes aliphatic-aromatic dihydroxy compounds for use as controlled drug delivery systems.
WO 97/39738 describes preparation of microparticles of a sustained release ionic conjugate comprising a free carboxyl group containing biodegradable polymers and a free amino group-containing drug.